1. Field of the Invention
The present invention relates to a magnetic compass and, more particularly, to a combination compass, which can also be used as a whistle for producing sound.
2. Description of the Related Art
A conventional magnetic compass is generally comprised of a housing (case), a pivot-pin vertically mounted inside the case, and a magnetic needle supported on the pivot pin for determining direction by means of the induction of the magnetic field of the earth. A rotating dial may be provided and supported on the case for checking the variation between the North Pole and the magnetic north pole. FIG. 1 shows a magnetic compass of this design. As illustrated, the magnetic compass comprises a housing 10, a compass device 20 mounted inside the housing 10, a top cover 30 pivoted to one end of the housing 10, and a sight 40 pivoted to the other end of the housing 10. The sight 40 has a sighting hole 41 and a convex lens 42. The top cover 30 has an aiming hole 31. When in use, the user attaches one eye to the sighting hole 41 to view the object through the aiming hole 31, and then moves the sight to the convex lens 42 to view the graduated dial of the compass device 20 and to read the reading of the azimuth.
The aforesaid magnetic compass is for use outdoors, for example, when climbing mountains or camping. In order to provide more functions, magnetic compasses with scale are disclosed. Similar designs are seen in U.S. Pat. Nos. D411121, D349066 and D369982. These magnetic compasses can also be used to measure the distance from a map, or for drawing lines. When going to have an outdoor activity, one may carry a lot of thins including flashlight, whistle, and etc. It is therefore desirable to have multiple implements combined into a combination device.
The aforesaid magnetic compass has drawbacks recited as follows. The sighting hole of the sight is an elongated slot extended downwards from the top of the sight. When the user attaches one eye to the sighting hole to view the object, a portion of the eye is located above the view hole, which will be easily influenced by the surrounding scene, such that it is not easy to aim the object. Further, in order to avoid the error when aiming the object, the width of the aiming hole is designed as smaller as possible. However, the reflection of light generated at the bottom surface of the top cover around the opening of the aiming hole will also influence the user when the user aiming the small aiming hole.
The primary objective of the present invention is to provide a combination compass, which can be used as a compass for determining direction as well as a whistle for producing sound.
To achieve this objective of the present invention, the combination compass comprises a housing, a compass device mounted inside the housing, a top cover pivoted to one end of the housing and being capable of covering over the compass device. The top cover has a mouthpiece, a resonance chamber, an air passage connected between the mouthpiece and the resonance chamber, and a sound producing device disposed in the air passage and adapted to produce sound when the user blowing air into the mouthpiece with the mouth.
It is another objective of the present invention to provide a combination compass which is helpful for the user to aim the object. To achieve this objective of the present invention, the combination compass provided by the present invention comprises a sight having a flat sight plate on which a sighting hole is formed. When the user attaches the eye to the sighting hole, the pupil of the eye is masked by the periphery of the flat sight plate so that the eye is free from the interference of surrounding scene when viewing the object. In addition, the top cover of the combination compass is provided with an aiming hole having a first opening on the bottom side of the top cover and a seconding opening on the top side of the top cover. The inner diameter of the aiming hole gradually reduces in direction from the first opening toward the second opening. Therefore, no reflection of light is produced on the inside wall of the aiming hole to influence the user when the user viewing the object through the sight.